Catalyst regeneration



yventional compressors..

.eliminates the need for such items of equipment and, provides asimplified and more elcient v method and arrangement of apparatus foreilecntivelycarrying out the regeneration of spent catalyst. 'It will beevident to those skilled in the Patented Apr. 9, 1946 CATALYSTREGENEBATION John W. Loy, Bartlesville, Okla., assignor to PhillipsPetroleum Company, a corporation of Delaware Application April 17, 1943,Serial No. 483,425 2 (llaims.lk (Cl. 25g-242) This invention relates tocatalytic conversion o! hydrocarbons and more particularly to catalyticconversion of hydrocarbons with provision for regenerating orreactivating the catalyst after it has become so laden on-stream withcombustible carbonaceous material such as carbon that the rate ofconversion is no longer economical. Still more particularly it relatesto an improved process and apparatus for reactivating such a catalyst insitu.

The present invention is an improvement over the catalyst regenerationdisclosed in application Serial N0. 414.850, illed October 13, 1941.

In catalytic cracking operations where high carbon deposits areencountered, large volumes of air are required to burn off the carbonand regenerate the catalyst. With chamber-type operation and stationarycatalyst beds. it is essential that the regenerative gases be handled atpressures above atmospheric in order to decrease the diameter ofconveying conduits and decrease differential pressure drop acrossthesystem.

The air compression required is relatively costly both as to initialinvestment and operating cost. Also. a diluent such as steam or ue gasmust b'e used with the air to limit the temperature to a reasonablemaximum in burning off the carbon.

As it is generally advantageous to recover the heat of regeneration bymeans of waste heat boilers, the present invention contemplates. amongother things. the use `ozt' steam from such boilers to inject combustionair into the catalyst chambers. Steam is generated in waste heatboilers, which waste heat boilers serve as a quenching lmeans for theconversion step and recover the `heat from the spent regenerative gases.

The steam may acquire a pressure of 200 pounds per square' inch, forexample, andunder this pressure; itis forced through a-'st'eam Jet intothe catalyst chamber. 'I'he steamin going through the steam 'Jet has anaspirating action and draws airlo'r other free oxygen containing gas inwith -thelsteam,ywhich air supports combustion in therespective'catalyst beds.

` One of the main advantages of the present invention resides in thefact that it eliminates certain expensive items of equipment, includingcon- The present invention artythatthe practice of my invention greatlyreduces the investment cost, minimizes replacement expenses, andrequires relatively lowmaintenance and operation expense, both inequipment and in necessary personnel to handle the same.

In operation, superheated steam, at 200 pounds per square inch and 900F., for example, with inducted air or other i'ree oxygen containing gas,is injected into the top of the catalyst chamber,

the mixture of steam and air being at high enough temperature, such as800 F., and high enough air content. such as 10% b'y volume, to initiatecombustion of the carbon deposit. The steam expands through the jet athigh velocity, the kinetic energy resulting therefrom is sumcient toinject a mixture of steam and air into the chamber, whose staticpressure is less than the initial steam pressure. The spent reactivatedgases and steam are removed from the bottom of the catalyst chamber.Where the catalyst cham- I'ber employed is divided into a plurality ofcompartments, auxiliary jets using steam and air at lower temperaturesthan those indicated above are used to promote combustion of depositedcarbon in subsequent compartments, since admixture of the secondaryregenerative gas with the hot gas from initial combustion produces amixture at high enough temperatures to ignite the remaining carbon. Ineffect, higher free oxygen content is permissible in cool secondaryregenerative gas, and the total amount of gas handled is decreased.

It is a primary object of the present invention to employ the pressureof a diluent gas, such as steam, to maintain the required pressure in acatalytic process and further to pass the steam under pressure through a`iettingdevice and by the aspirator action of the :letting device, drawand then inject the necessary i'ree oxygen containing gas into theprocess, to support combustion during the regenerative step.

It is a further object of this invention to Drovide a system of thecharacter indicated which'is less expensive in initial, maintenance, andoperating costs than similar systems for regenerating spent catalyststhat have been employed heretofore.

It is a still further object of the invention to conserve on the amountof critical metals employed in carrying out a catalyst regenerationprocess.

Other objects and advantages will appear from the description as itcontinues and from the annexed drawing which is a diagrammatic view orthe process.

Referring to the drawing, a catalyst chamber I is provided at itstopfwitn an :niet 2. a suitable hydrocarbon feed stock is supplied toinlet 2 durbottom of the catalyst chamber for removing convertedhydrocarbons by way of a line l or alternatively for removing spentreactivating gases by way of a line 1.

For the purpose of illustration only, I have shown catalyst chamber I asbeing divided into a plurality of compartments or sones I, I, Il and Ilof progressively increasing volume reading downwardly. It is to beunderstood that my invention may be effectively practiced whether thecatalyst chamber is divided into a plurality of compartments, asillustrated, or whether it consists of a 'single compartment.Furthermore, while four compartments or sones are denoted in thedrawing, it will be apparent that any desired suitable number of sonesmay be employed. with equal success. The sections are separated bylmaterial that is supported on and above leach member I2.

As was indicated above, a diluent. such as super-heated steam, withinducted air is supplied to the top of the chamber at desired pressureand temperature. The diluent. preferably steam, is conducted throughline 4 to a letting device or inlector Il. A line I1 transmits a freeoxygen containing gas, such as air, to letting device It. As the steamis letted through device II, it draws or inspirates air from line I 1,the steam and air being thoroughly mixed within device Il and thenaspirated into upper sone l of the catalyst chamber. It will be apparentthat the mixture of steam and air may be forced into the chamber byvirtue of the kinetic energy developed while these materials are beingpassed through letting device Il.

Mixing zones I3, I4. and Il are provided between the catalyst beds..'Ihe hot gases issuing from top sone a are admixed with freshreactivated gas and steam that are introduced through letting devices orinlectors Il, Il. and 2l as the gas and steam pass downwardly throughcatalyst zones l, Il, and II, respectively. The resulting mixture ofiluid materials in the various sones at desired temperature, volume, andoxygen content passes through each lower bed successively and burns thecarbon deposited on the spent catalyst to thereby reactivate thecatalyst. It will be evident that the temperature developed in thevarious sones should be such as not to exceed the safe limits of thematerials of the chamber, and further, so as not to inlure the catalystitself in the course of reactivation. The recommended range oftemperatures for safely and emciently operating the system is generallybetween "100 and 1500 l".

The enluent products, when the process is on assenso steam, that may begenerated in the practice of this invention, to other uses. Line Il maybe employed to supply additional steam from a suitable source when suchadditional steam is required in the process. Valved line 2| conducts thesteam to valved lines 21, 2l, and Il which in turn connect into theletting devices Il, Ii, and Il, respectively. .Connecting into each ofthese letting devices are the valved air lines Il, SI, and l2. The steampassing through the letting devices draws in air through the lines l.,II. and Si and mixes the air with the steam before the mixture passesinto the sones Il, Il, and I l. The action of letting devices Il, Il.and Il is the same as that of letting device Il. described above.

It is thought that the operation is obvious without any further detaileddescription thereof. The operation of the catalyst chamber, both onwnversion and reactivation is fully discussed in 8erial No. 414,850,filed October 18, 194i, and since the catalyst chamber is the same.reference is made to this application for a full understanding of itsoperation.

The letting devices II, Il, II. and 2l are a standard article ofcommerce, available from any number of sources making equipment tohandle steamJ generation anddistribution, and applicant makes no claimof novelty for the specific letting devices employed. The free oxygencontaining gas supplied by lines I1, il, Il. and for I2 may be either atatmospheric or superatmospheric pressure, as desired. The pressure ofthis gas before it is admitted into the corresponding letting devicesshould be auch that pressure' of the combined diluent, such as steam andair. will be sufilcient to carry out the purposes this invention.

It is recommended and within the purview of this invention to recyclespent regenerative gas from line 'I to lines I1, Il, II, and for I2 whenit is found that the conditions for operating the catalyst chamber inregenerating spent catalyst warrants the use of more diluent than thatnormally supplied to the catalyst chamber downstream of the individualletting devices.

yIirom the foregoing, it is believed that the method and apparatus ofthe present invention will be readily comprehended by persons skilledthe conversion cycle, or spent regenerative gases,

.generating gases admixed with a steam diluent is contacted with saidcatalytic material under combustion conditions in a regeneration sone toremoved said carbonaceous material, wherein the catalytic material insaid regeneration sone is arranged in a series of beds having freespaces therebetween, and wherein oxygen-containing regenerating gas isintroduced intoeachof said beds under combustion conditions to effectregeneration thereof, wlich comprises nowing hot combustion gases fromsaid regeneration sone in heat exchange with a stream of water,generating superheated steam at elevated pressure thereby. flowing saidsuperheated steam through a plu.- rality of injector means eachcommunicating with spaanse a source ot free oxygen-containingregenerating gas, admixing said oxygen-containing regenerating gas withsaid steam by the inspirating action of said steam in passing throughsaid injector means, and directly injecting said mixture into each ofsaid free spaces whereby intimate mixing thereof with combustionproducts iiowing from the preceding -bed and distribution into thesucceeding bed occurs, and maintaining combustion conditions in each oi'said beds in order to eiect combustion of the carbonaceous materialtherein.

2. A catalyst regeneration system which comprises a catalyst chamber. aseries of spaced catalyst beds in said chamber, a plurality oi injectormeans each positioned immediately adjacent to a corresponding spacebetween said beds, one of said injector means being positioned ahead ofthe iirst bed in said series to directly introduce oxygen-containingregeneration gas under combustion conditions into the spaces betweensaid beds and ahead o! the rst or said series of beds. means forremoving hot combustion gases from said chamber, a waste heat boiler,means for owing said hot combustion gases through said waste heat boilerin heat exchange with a stream of water introduced therein to generatesteam under pressure, means for flowing said steam through said injectormeans, a source o! free oxygen-containing gas communicating with saidinjector whereby said gas is admixed with said steam by the inspiratingaction thereof to form the oxygen-containing regeneration gas and isinjected into said spaces in a manner to eiIect intimate mixing of saidsteam and oxygen-containing gas with the products of combustion from thepreceding bed in said spaces and ahead of said first bed by the kineticenergy of said steam.

JOHN W. I DY.

